Twitter is going shopping in Boston again. Just a few months after acquiring Crashlytics and Bluefin Labs, the social media giant is buying Spindle, a local-discovery Web startup, and relocating the team to San Francisco. Now the flow of tech talent is going both ways, as Hopkinton data-storage giant EMC is reportedly acquiring ScaleIO, an Israeli startup now based in Silicon Valley, for over $200 million. It’s all part of the ongoing competitive dynamic between East and West coast companies.

In other innovation news…

-The biotech IPO express keep chugging along. Cambridge-based Bluebird Bio has gone public on the Nasdaq, raising $100 million and seeing its shares soar by more than 50 percent.

-Meanwhile, Healthbox has graduated its second class of healthtech startups in Boston. The Chicago-based accelerator program is trying to feed emerging technologies to the healthcare industry, and plans to return to Boston next year.

-And finally, the CEO of Akamai, Tom Leighton, laid out the roller-coaster story of his company at our XSITE conference this week. The upshot is that while markets, technologies, and people may change, attitude does not. So his overarching advice to entrepreneurs is: be tenacious.